1. Field of the Invention
The present invention relates in general to a pedestrian protection apparatus for a vehicle, and in particular to an improved structure of the pedestrian protection apparatus disposed at a lower part of a front face of the vehicle and arranged to sweep a leg portion of a pedestrian by contact with the leg portion of the pedestrian that has collided with or contacted the front face of the vehicle, thereby protecting the leg portion of the pedestrian.
2. Discussion of Related Art
In vehicles such as automotive vehicles, there are conventionally disposed, at a front face, a rear face, or a side face, of the vehicles, various types of protection apparatus which absorb an impact energy generated upon a collision for thereby protecting a vehicle body and passengers of the vehicle. In recent years, there is disposed, at the front face of the vehicle, an apparatus for protecting a pedestrian upon collision or contact of the pedestrian with the front face of the vehicle.
As one type of the pedestrian protection apparatus, there is known a so-called leg-sweep apparatus which is disposed inside of a front bumper or disposed independently of the front bumper. The leg-sweep apparatus is arranged to apply, to a leg portion of the pedestrian, counterforce with respect to an impact load that is inputted upon collision of the pedestrian with the front face of the vehicle and sweep (scoop up) the leg portion of the pedestrian, thereby causing the pedestrian to fall down or to be thrown over toward the vehicle. Thus, it is possible to minimize occurrence of injuries to the knee such as bone fractures, thereby assuring protection and safety of the pedestrian.
Examples of the leg-sweep apparatus as one type of the pedestrian protection apparatus are disclosed in a patent publication document 1 (JP-A-2001-277963) and a patent publication document 2 (JP-A-2004-25976), for instance. The pedestrian protection apparatus disclosed in the patent publication document 1 is arranged to be disposed at the lower part of the front face of the vehicle and includes resin foam body which extends in a vehicle width direction with at least a part of the resin foam body protruded from the front face of the vehicle and a beam member which extends in the vehicle width direction while being in contact with the back surface of the resin foam body. The pedestrian protection apparatus disclosed in the patent publication document 2 is arranged to be disposed at the lower part of the vehicle and includes a metal pipe or the like which is fixed to the lower part of the front face of the vehicle so as to extend in the vehicle width direction. However, the pedestrian protection apparatus disclosed in those documents have drawbacks which should be rectified. In the former pedestrian protection apparatus including the resin foam body and the beam member, the number of the components is undesirably large, and therefore the cost of the components is high. Further, it is troublesome to install or mount the apparatus on the vehicle. In the latter pedestrian protection apparatus including the metal pipe, the weight of the apparatus inevitably increases. In addition, it is difficult to form into a configuration following that of the front face of the vehicle.
Under such situations, there has been proposed, in a patent publication document 3 (JP-A-2004-203183), for instance, a pedestrian protection apparatus arranged to be disposed to extend in a frontward and backward direction of a vehicle. The disclosed apparatus includes a plate member which is formed of a synthetic resin, which includes a front portion and a rear portion, and which is fixed at the rear portion to the vehicle with at least a leading end part of the front portion protruded from the front face of the vehicle. The pedestrian protection apparatus disclosed in the patent publication document 3 is arranged to sweep a leg portion of a pedestrian that has collided with the front face of the vehicle by contact of the leading end part of the front portion of the plate member protruding from the front face of the vehicle, with the leg portion of the pedestrian. In this conventional pedestrian protection apparatus, there are formed, on one surface of the front portion of the plate member, a plurality of first ribs having a planar shape and extending in the frontward and backward direction of the vehicle and a plurality of second ribs having a planar shape and extending in the width direction of the vehicle, which first and second ribs are assembled in a lattice. In this structure, the front portion of the plate member is reinforced, that is, the rigidity of the front portion of the plate member is increased, owing to the ribs formed thereon.
In such a pedestrian protection apparatus, the number of the components is small. Further, the plate member whose leading end part is protruded from the front face of the vehicle is made of the synthetic resin that is excellent in formability. Accordingly, the disclosed apparatus assures protection of the pedestrian while eliminating the drawbacks of the above-indicated apparatus including the resin foam body and the beam member and the drawbacks of the above-indicated apparatus including the metal pipe. Further, the front portion of the plate member is reinforced, that is, the rigidity of the front portion is increased, by the plurality of first and second ribs formed as described above, whereby, when the front portion of the plate member comes into contact with the leg portion of the pedestrian, the front portion is prevented from being deformed due to impact upon the contact or the deformation amount of the front portion is made sufficiently small. Therefore, it is possible to stably assure counterforce with respect to the impact load inputted to the plate member.
However, the conventional pedestrian protection apparatus having the plate member formed of the synthetic resin experiences the following drawbacks.
The above-described pedestrian protection apparatus is generally disposed inside of the front bumper such that the planar second ribs provided on the front portion of the plate member are opposed to the inner surface of the front bumper. The cross sectional shape of the front bumper taken along a vertical plane which is parallel to the frontward and backward direction of the vehicle is a convex curved shape protruding forward. Where the inner surface of the front bumper has a convex curved surface configuration in correspondence with the shape of the front bumper, there is inevitably formed a comparatively large clearance between the inner surface of the front bumper and the planar second ribs of the plate member.
Further, in the pedestrian protection apparatus described above, in general, the leading end part of the front portion of the plate member is positioned so as to protrude from the front face of the vehicle with the rear portion of the plate member fixed to a radiator support, a cross member or the like. Accordingly, the dimension of the plate member as measured in the frontward and backward direction of the vehicle is relatively large. The increase in the dimension of the plate member as measured in the frontward and backward direction of the vehicle, however, leads to insufficient rigidity (insufficient strength with respect to deformation) against the impact load inputted thereto upon collision of the leg portion of the pedestrian with the front face of the vehicle. Where the flexural or bending rigidity of the plate member is insufficient, the front portion of the plate member is initially deflected or bent with ease, so that the timing of initial rise of the impact load in the load characteristics (abrupt rise of the load in the load-displacement curve) is delayed, thereby making it impossible to instantaneously exhibit sufficient counterforce with respect to the impact load. In this case, the pedestrian protection apparatus fails to instantaneously or promptly sweep the leg portion of the pedestrian.
In the meantime, as the pedestrian protection apparatus which is to be disposed inside of the front bumper with the leading end part of the front portion of the plate member opposed to the inner surface of the front bumper having the convex curved surface configuration, there is known a structure that the surface of the leading end part of the plate member that confronts the inner surface of the front bumper is made as a convex curved surface corresponding to the inner surface of the front bumper, as disclosed in a patent publication document 4 (JP-A-2002-274298), for instance. The disclosed structure prevents formation of a large clearance between the leading end part of the plate member and the inner surface of the front bumper.
In the pedestrian protection apparatus having such a structure, however, the impact load that acts in a backward direction of the vehicle when the leg portion of the pedestrian collides with the front bumper is inputted to the convex curved surface of the leading end part of the plate member. Accordingly, upon the input of the impact load, there is a generated force that lifts up the leading end part of the plate portion. In this instance, the leading end part of the plate member is deformed so as to be rolled up, resulting in a delay in the rise of the impact load in the load characteristics. Accordingly, the pedestrian protection apparatus in which the leading end part of the plate member has a shape that corresponds to the shape of the inner surface of the front bumper also suffers from the problem that the leg portion of the pedestrian cannot be promptly swept.